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FDA Highlights Breakthrough Breast Cancer Treatments at SABCS

FDA Highlights Breakthrough Breast Cancer Treatments at SABCS

Published on December 14, 2020

FDA Highlights Recently Approved Breast Cancer Treatments

The U.S. Food and Drug Administration (FDA) highlighted three recently approved breast cancer treatments during the recent San Antonio Breast Cancer Symposium, including two antibody-drug conjugates. Antibody-drug conjugates are designed to deliver toxic drugs directly to cancer cells. The antibody component binds to a specific protein on the surface of the cells.

“Antibody-drug conjugates are an important new drug class,” said Dr. Angela DeMichele, a professor of medicine and co-leader of the Breast Cancer Center at the University of Pennsylvania Abramson Cancer Center. “These agents have specific features that adapt across breast cancer subtypes.”

The treatments were approved through the FDA’s Breakthrough Therapy designation process, which is designed to expedite the development and review of drugs that are intended to treat a serious condition when preliminary clinical evidence indicates the drug may demonstrate substantial improvement over available therapy.

Here are the details of the three treatments presented at the FDA and Breast Cancer Workshop:

Drug name:  Trodelvy (sacituzumab govitecan-hziy)

Approval Date: April 22, 2020

Significance: The first antibody-drug conjugate approved for triple-negative breast cancer (TNBC)

Indication: Adults with TNBC that has spread (metastasized) to other parts of the body. Patients must have already undergone at least two prior treatment regimens.

How it Works: The new agent links a humanized monoclonal antibody, sacituzumab, and the chemotherapy drug SN-38 and targets a protein called Trop-2. Trop-2 is present at high levels in TNBC and other cancers. When sacituzumab and Trop-2 interact, the entire antibody-drug conjugate is pulled into the cancer cell. Once inside the cell, SN-38 is released and kills the cancer cell.

Trial results: One-third of the 108 patients who received sacituzumab govitecan had their tumors shrink by at least 30%. The response lasted an average of 7.7 months. Both are significantly better than earlier third-line TNBC options eribulin and ixabepilone.

Name: Enhertu (trastuzumab deruxtecan) (TDX-d)

Approval Date: December 19, 2019

Indication: Patients with unresectable or metastatic HER2-positive breast cancer who have received two or more prior anti-HER2-based regimens in the metastatic setting.

How It Works: Enhertu is made up of three parts: trastuzumab, the monoclonal antibody that targets HER2; deruxtecan (DXd) a topoisomerase I inhibitor chemotherapy that is more potent than other topoisomerase inhibitors; and a compound that links trastuzumab to DXd. The antibody guides DXd to the cancer cells and then releases it.

Trial results: Of 184 female patients, the overall response rate was 60.3% with a 4.3% complete response rate and a 56% partial response rate. The median duration of response was 14.8 months.

Name: Tukysa (tucatinib)

Approval Date: April 17, 2020

Significance: First agent to be approved for HER2+ breast cancer with brain metastases.

Indication: Tukysa is used with trastuzumab (Herceptin) and capecitabine (Xeloda) to treat adults with HER2+ breast cancer that has spread to other parts of the body such as the brain, or that cannot be removed by surgery, and who have received one or more anti-HER2 breast cancer treatments.

How It Works: Tukysa is a tyrosine kinase inhibitor, a class of drugs that work by binding to enzymes called tyrosine kinases that are part of the HER2 protein that is inside the cell. It prevents the enzyme from sending signals that promote cell growth. 

Trial results: Of 612 patients, about half had active or stable brain metastases. The median time without progression in patients who received Tukysa, trastuzumab and capecitabine was 7.8 months compared to 5.6 months in those patients who received placebo, trastuzumab and capecitabine. The median overall survival in patients who received Tukysa, trastuzumab and capecitabine was 21.9 months compared to 17.4 months in patients who received placebo, trastuzumab and capecitabine.

~Megan Trusdell

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